310 P. W. Flanagan and F. L. Bunnell 



100 



c 



90 



- 



o 



» 80 



Z 70 



60 



Va 



n. 



T — I — I — I — I — I — I — I — I — I — I — I— I — I — r 



^ 



Live 



J L 



Dead 



J u 



_u 



JJASONDJFMAMJJASO 



FIGURE 9-7. Progression of leaf weight of 

 Carex aquatilis and Eriophorum angustifolium, 

 combined. Hatched bar shows the amount of 

 material removed in vitro by warm water and 

 80% ethanol. Vertical bars indicate the standard 

 errors. The dashed line indicates the weight loss 

 before ingress of microorganisms is well under 

 way. (Flanagan, unpubl.) 



function of substrate chemistry. The third, abisko ii (Bunnell and 

 Scoullar 1975), integrates the effects of changing meteorological condi- 

 tions and substrate chemistry within an ecosystem framework. The 

 models document relationships between weight loss and microbial activi- 

 ties, as they are influenced by abiotic variables and substrate chemistry 

 and the relationship of the biomass of microbial populations to primary 

 production and turnover of organic matter. Although the development 

 of these models was based on tundra research, their predictive abilities 

 have also been tested for conditions found in the taiga and moors (Bun- 

 nell et al. 1977a, Bunnell and Scoullar 1981). 



Temperature, Moisture, and Microbial Respiration 



The function GRESP represents a formal statement and complex hy- 

 pothesis of the manner in which temperature, moisture and substrate fea- 

 tures influence aerobic respiration of microbes. It treats aerobic respira- 

 tion as a function of the supply rates of water, oxygen and organic nutri- 

 ents. The critical features of the hypothesis are presented: 



R{T.^4) = [M/f^a, +M)][ff2/(ff,+M)] «3a4'^-'°'^'° 



where R{T,M) = ^A CO2 respired (g substrate)"' hr"' at temperature T 

 and moisture M 



